Abstract

We demonstrated the fabrication of a phase shaper for generating a ‘doughnut mode’ laser beam using a thin, circular polymer film on a substrate. The fabrication method is based on a combination of spin-coating and drop-casting. The alignment procedure to get ideal ‘doughnut modes’ is described. The intensity distribution at the focus is analyzed with single molecule spectroscopy.

Phase shift as a function of concentration of PMMA solution. The phase shift at the center the circular polymer structure is analyzed from the shift of the fringes. One fringe shift corresponds to 2π phase shift.

The Intensity distribution of phase shaped laser beam. (a) Schematic of the diameter of the phase shaper (A) and that of the laser beam (B). The ratio of the diameter of the laser beam and that of the phase shaper (B/A) are (b) 1.30, (c) 1.39, (d) 1.41, (e) 1.48, and (f) 1.56, respectively.